Bently 3500/42M-01-00 Composite Probe Sensor System

In Triple Modular Redundant (TMR) configurations, the deployment of 3500/42 monitors and Proximitor/Seismic TMR I/O Modules demands a strategic approach to ensure redundancy and accurate operation. This configuration involves the installation of monitors adjacent to each other in groups of three, employing two distinct types of voting mechanisms to prevent single-point failures.

Key Components:

1. Installation Requirement:
   • In TMR configuration, 3500/42 monitors and Proximitor/Seismic TMR I/O Modules must be installed adjacent to each other in groups of three.
2. Voting Mechanisms:
   • Two types of voting are employed to ensure accurate operation and avoid single-point failures.
     • The first level involves voting on the TMR Relay Module, comparing selected alarm outputs using a 2 out of 3 method.
     • The second level, called “Comparison” voting, compares proportional value outputs of each monitor in the group.
3. Comparison Voting Configuration:
   • Configure comparison voting using the Rack Configuration Software by setting parameters such as “Comparison” and “% Comparison.”
   • Comparison:
     • Determines how far apart the values of the three monitors can be before an entry is added to the System Event List.
   • % Comparison:
     • Sets the highest allowed percent difference between the middle value of the three monitors and the individual values of each monitor.
4. Input Configurations:
   • For TMR applications, two types of input configurations are available: bussed or discrete.
     • Bussed Configuration:
       • Uses the signal from a single nonredundant transducer, providing that signal to all modules in the TMR group through a single 3500 Bussed External Termination Block.
     • Discrete Configuration:
       • Requires three redundant transducers at each measurement location, with each transducer’s input connected to separate 3500 External Termination Blocks.

Conclusion: Implementing TMR configurations with 3500/42 monitors involves careful installation and configuration to ensure redundancy and accurate operation. The combination of relay module voting and comparison voting mechanisms, along with considerations for input configurations, contributes to a robust and reliable monitoring system, minimizing the risk of single-point failures in critical machinery applications.